Method of graphical objects recognition using the integrity principle

ABSTRACT

The present invention discloses a method to increase reliability, correctness of objects recognition process by performing a recognized object description as a set of special standard elements along with the spatial and parametrical correlation thereof.  
     The said standard elements are preliminarily assigned graphic structures of elementary form and of easy identification and recognition. They may be provided with spatial and/or parametric details and thus may describe any object on the image including characters of text.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to character recognitionon a bit-mapped binary image or other binary or raster images and moreparticularly to recognition of non-text and/or text objects on thedocument image.

[0003] The abovementioned methods are also used in forms recognition.Said forms combine portions of typographical and hand-written text alongwith a set of special reference points meant for orientating on thedocument or form. Some examples of of forms are questionnaires, bankinvoices of fixed or non-fixed field layout.

[0004] Said methods can be also used for the recognition of objects ofany pre-defined kind on a bit-mapped image.

[0005] 2. Prior Art

[0006] Segmentation and parsing methods are known in the art.

[0007] Today there is a number of known methods of image recognition ona bit-mapped image by performing a comparison between an obtained imagein the form of initial image units aggregate (commonly pixels) and amodel image of the whole object or a set of possible object'sembodiments stored in a special reference means usually termedclassifier.

[0008] A known group of methods of text recognition comprises parsingthe document into parts presumably containing images of letters with thefurther comparison of said images with those stored in one or morespecial feature and/or raster classifiers.

[0009] The said method is disclosed, for example, in U.S. Pat. No.5,680,479 (Oct. 21, 1997, Wang, et al.).

[0010] A similar method is disclosed in U.S. Pat. No. 5,684,891 (Nov. 4,1997, Tanaka, et al.). The document describes a method of image parsingthat enables to pick out a separate character images, which in theauthor's opinion makes the process more reliable. The character image asan aggregate of pixels is then compared with the model from aclassifier.

[0011] A shortcoming of the method is that it uses full-sized images andfull-sized models for comparison, which inevitably reduces theproductivity of the process.

[0012] Therefore, the target of the present invention is to increase thereliability of objects recognition, to increase the noise immunity.

SUMMARY OF THE INVENTION

[0013] A method of objects recognition is disclosed.

[0014] The present invention discloses a method of objects recognitionby comparing the recognized object image with the model, described as aset of standard elements of a limited number of types along withspatially parametrical correlation thereof. Said standard elements arepreliminarily assigned graphic structures of simple (elementary)geometrical form and of easy identification and recognition on theimage. The said standard elements may be provided with spatial and/orparametric details (characteristics) and thus may describe any objectincluding characters of text.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1. shows examples of prime standard elements.

[0016]FIG. 2. shows some possible variants of a recognized object'simage appearance as sets of standard elements by the example ofcharacter “B”.

[0017]FIG. 3. shows some examples of complicated standard elements.

DETAILED DESCRIPTION OF THE INVENTION

[0018] A method of graphical objects recognition is disclosed.

[0019] The present invention discloses a method of increasing thereliability, correctness of objects recognition process by performing arecognized object description as a set of standard elements.

[0020] The said target of the invention is achieved by the preliminarilyassignment of graphical structures of a simple (elementary) geometricalform as standard elements suitable to form the models of recognizedobjects. Said standard elements can be reliably identified due to thesimple geometrical form thereof.

[0021] Each said standard element comprises more then one pixel (initialgraphical unit).

[0022] Each recognized object is described as comprising one or morepreliminarily assigned standard elements as parts along with thecorresponding spatially parametric correlation thereof. The recognizedobject may comprise standard elements of one or more types. They candiffer in relative spatial location (attitude, position), size and/orother parameters.

[0023] Recognized objects can be of various kinds: document designelements, special graphical elements, reference points or the like,meant for orientating on the document or form, text elements, charactersof printed and/or hand-written type including.

[0024] The essence of the invention is as follows.

[0025] One or more types of graphical elements of simple form arepreliminarily assigned as standard elements to compose the recognizedobjects. Some of the examples of standard elements are: straight-linesegment, circle, oval, arc etc.

[0026] Said standard elements are remarkable for their highidentification and recognition reliability in the image, due to theirgeometrical simplicity.

[0027] Said standard elements may differ in spatially—parametricalcharacteristics. For example, a straight-line segment may differ inlength, incline angle, line thickness (absolute and/or relative) etc.;an arc may differ in angle, radius of curvature, orientation etc.

[0028] Said standard elements may comprise white portions—areas withwhite color, not black or other colored and even transparent.

[0029]FIG. 1 shows the examples of basic standard elements.

[0030] The classifier (reference means) to be used for objectsrecognition (characters, reference points, other kinds of graphicalelements) is filled with object's descriptions in a form of sets ofcomposing standard elements, along with positional relationship andspatially parametrical correlation thereof.

[0031] The said classifier is also filled with possible deviations ofrecognized object's image as additional sets of standard elementscomposing the said object along with positional relationship andrelative and/or absolute dimensions thereof. The said descriptions maydiffer greatly either by the set of standard elements or by theirspatially parametrical correlation. Some possible variants of arecognized object's appearance via standard elements sets by the exampleof character “B” are shown on the FIG. 2.

[0032] Then the image is processed to identify and recognize standardelements.

[0033] Groups of standard elements presumably composing an object areselected. For each said group the hypothesis is set up and tested aboutthe belonging of all set of elements as a whole to a supposed objectdescribed in the classifier.

[0034] In the case of not enough reliable result of the said hypothesistest a new hypothesis is set up and tested about the belonging of allset of elements as a whole to another supposed object described in theclassifier.

[0035] After all possible hypotheses testing the most reliable variantof the object is selected. In the case of ambiguous result of hypothesestesting supplementary information or supplementary recognition methodscan be used.

[0036] Said standard elements may compose more complicated standardelements by joining up into various combinations of elements of similaror various types with different positional relationship and sizethereof. For example, a composition of horizontal and verticalstraight-line segments forms complicated standard element cross.

[0037] Some examples of complicated standard elements are shown on theFIG. 3.

[0038] The set of the standard elements composing recognized object maybe described in a form of alternative.

[0039] A spatially parametrical correlation of standard elements may bedescribed as an alternative.

[0040] Standard elements may partly contain portions of white color, nocolor or even be transparent.

[0041] The recognized object description may be realized in the form ofinterval for one or more spatially parametrical correlation values.

[0042] The recognized object description may be also realized as a setof standard elements connected by relations of mathematical logic, of“AND” type, of “OR” type, of “NOT” type including.

[0043] The standard elements correlation in a recognized object may beexpressed in the form of more then a single-level structure.

We claim:
 1. A method of object recognition on a bit-mapped image,comprising parsing the image into regions, identifying text and non-textregions, recognition of objects, preliminarily assigning at least onegraphical structure comprising more then one primary graphical unit tobe used as a standard element that may compose as a part at least onerecognized object, preliminarily describing at least one recognizedobject as a set of said standard elements of at least one type alongwith spatially parametrical correlations thereof, performing thefollowing steps search and identification of at least one standardelement on the said bit-mapped image, selection of at least one standardelement image for testing on belonging to the recognized object, settingup and testing a hypothesis about the recognized object on the basis ofthe image formed by all aggregate of said selected standard elementimages as a whole taking into account spatially parametricalcorrelations thereof.
 2. A method of character recognition on a bitmapped image, comprising parsing the image into regions, identifyingtext and non-text regions, identifying regions containing characters,recognition of characters, preliminarily assigning at least one type ofgraphical structure comprising more then one primary graphical unit tobe used as a standard element that may compose as a part at least onerecognized character, preliminarily describing at least one recognizedcharacter as a set of said standard elements of at least one type alongwith spatially parametrical correlations thereof, performing thefollowing steps search and identification of at least one standardelement on the said bit-mapped image, selection of all standard elementsin the region presumably containing image of character for testing onbelonging to a recognized character, setting up and testing a hypothesisabout the recognized character using the image formed by all aggregateof said selected standard elements as a whole taking into accountspatially parametrical correlations thereof.
 3. The method as recited inclaims 1 or 2, wherein at least one standard element composing therecognized object is described as an alternative.
 4. The method asrecited in claims 1 or 2, wherein the set of standard elements composingthe recognized object is described as an alternative.
 5. The method asrecited in claims 1 or 2, wherein at least one standard elementcomposing the recognized object is described as an interval.
 6. Themethod as recited in claims 1 or 2, wherein the image at least partlycontain standard elements connected by relations of mathematical logic.7. The method as recited in claims 1 or 2, wherein the step ofrecognized image identification as a standard elements aggregateadditionally comprise analysis of elements connected by relation of“AND” type, analysis of elements connected by relation of “OR” type,analysis of elements connected by relation of “NOT” type.
 8. The methodas recited in claims 1 or 2, wherein said standard elements correlationsin the recognized object are expressed in the form of more thensingle-level structure.
 9. The method as recited in claims 1 or 2,wherein said standard elements at least partly contain portions of whitecolor.
 10. The method as recited in claims 1 or 2, wherein said standardelements at least partly contain transparent portions.
 11. The method asrecited in claims 1 or 2, wherein in the case of ambiguous result ofhypotheses setting up and testing a supplementary information is used.12. The method as recited in claims 1 or 2, wherein in the case ofambiguous result of hypotheses setting up and testing supplementaryrecognition methods are used.
 13. The method as recited in claims 1 or2, wherein the said standard element is composed of more prime standardelements of at least one type.
 14. The method as recited in claims 1 or2, wherein the description of a recognized object as a set of standardelements and spatially parametrical correlation thereof is placed intothe special means for storage and search.